Question: Tiffany starts counting at 23, and she counts by threes. If 23 is the 1st number that Tiffany counts. what is the 13th number that she counts?
Explanation: What is the first number that she counts? $23$ What is the second number that she counts? $\begin{align*}&23 + 3 \\ &= 26\end{align*}$ What is the third number that she counts? $\begin{align*}&23 + 3 + 3 \\ &= 23 + (2 \times 3) \\ &= 29\end{align*}$ What is the 13th number that she counts? $\begin{align*}&23 + (12\times3) \\ &= 23 + 36 \\ &= 59\end{align*}$